Glycosylphosphatidylinositol (GPI) is a complex glycolipid that anchors many proteins to the cell surface. The biosynthetic pathway of GPI is mediated by sequential addition of sugars and other components to phosphatidylinositol. PIGV adds the second mannose to the GPI core (Kang et al., 2005 [PubMed 15623507]).[supplied by OMIM